This paper presents a novel approach for functional coverage analysis automation. It is well known that functional verification is a real bottleneck in any digital design development. Consequently, it is necessary to develop new methodologies to increase the quality of functional verification. A metric that measures the functional coverage is specific to each design, and it depends on its functional requirements. Hence, we propose a methodology supported by a tool that automates the coverage analysis at the functional level. Our tool takes as entry a standard executable specification and generates test bench components aimed at performing a functional coverage analysis on a specific design. We use functional metrics as parameters in our tool and apply theses metrics on an executable specification. Using our methodology, we are able to provide a quantitative evaluation of test suites developed to exercise the functionality defined in an executable specification. The application of these test suites on a RTL design improves error detection, through a better exploration of the design It also increase the degree of confidence in the design.